Mobile computing devices have seen explosive growth over the past few years. With growing computational power and memory capacity, personal computing devices, have become essential tools of modern life, providing telephone and text communications, navigation, photo and video functionality in a package that fits in one's pocket. As a result of providing so many different types of radio frequency communications services and displaying high-quality video, many smart phones and similar mobile computing devices are now require multiple antennas capable of transmitting and receiving (transceiving) radio signals over a variety of networks and associated bandwidths. However, the operation of multiple antennas often requires that each of the multiple antennas be isolated some distance away from one another to avoid interference or antenna coupling. In smaller sized mobile computing devices, such as the size of a wristwatch, the limited real estate prevents the effective implementation of multiple antennas without resulting in antenna coupling. Without such isolation, the mobile computing device may not operate properly as the presence of the other antennas creates performance degradation in the form of antenna coupling even though some of the antennas are not energized at the same time in the operation mode.
Some conventional devices have attempted to provide a single antenna configured to transceive radio signals over multiple networks and multiple frequency bandwidths. However, such devices with a singular antenna serving multiple networks and frequency bandwidths often provide sub-optimal performance in each of multiple networks and bandwidths. In order to allow a singular antenna to service all of the desired bandwidths and networks, additional circuitry is required to distinguish radio signals for each of the desired networks and frequency bandwidths. Such additional circuitry may increase the total cost, power consumption and volume of the mobile computing device. Moreover, a singular antenna prohibit a capability to have simultaneous operation of the radio functionality in different frequency bands.
It is desirable, therefore, to enhance the capability of simultaneously operating antennas; for instance, simultaneous among WWAN, Bluetooth, and GPS antenna. To do so, the antenna design should mitigate coupling that degrades performance. It is further desirable to increase the number of operating bands of the one or more antennas in a single wireless device in order to operate in more geographic areas. It is also desirable to reduce the size (“real estate”) of printed circuit boards by requiring fewer RF components in order to support smaller and more economical wireless devices.